Referring to FIG. 1 of the drawing, a prior art dental abutment 10 has an upper segment 11, and a lower segment 12 which is provided at the free end with male threads 121. The upper segment 11 is dimensioned to fit into a tooth “T”, while the lower segment 12 is fastened with an implant 20 such that the male threads 121 of the lower segment 12 are engaged with female threads 22 of a cavity 21 of the implant 20. The engagement is reinforced by a cement “G” which is injected into the cavity 21.
As shown in FIG. 2, a socketed bone “I” is provided with a socket into which the implant 20 is fitted. In other words, the tooth “T” is implanted in the bone “I” in conjunction with the abutment 10 and the implant 20. In view of the fact that the application of the cement “G” can not be easily controlled with precision in terms of quantity of the cement “G”, it is therefore likely that an excessive amount of the cement is injected into the cavity 21 of the implant 20, thereby resulting in the spilling of the cement “G”. The cement residue is often deposited on the outer surface of the lower segment 12 of the abutment 10, as well as on the top end of the implant 20, as shown in an enlarged view of a circled portion of FIG. 2. In the event that the cement residue is not removed properly, the socketed bone “I” and the tissue surrounding the socketed bone “I” will fail to grow together intimately. Such a mishap often results in a gums inflammation, or a situation in which the implant 20 is apt to become loosened by a chewing action. In order to avert such an operational deficiency as described above, a complete removal of the cement residue from the lower segment 12 of the abutment 10 and the top end of the implant 20 is called for at the expense of the patient.
The abutment 10 described above is used in an upright manner in the molar implantation; nevertheless it is not suitable for use in the incisor implantation. As shown in FIGS. 3A, 3B, and 3C, the socketed bone “I” of the incisor has an inclination. Accordingly, the implant 20 must be inserted into the socketed bone “I” at an angle θ corresponding to the inclination of the socketed bone “I”, as shown in FIG. 3A. As a result, an abutment 100 with an inclination is used to implant an incisor “T”. The abutment 100 is provided in the center with an axial through hole 101 and is fastened with the implant 20 by a fastening screw “S” which is engaged with the female threads 22 of the cavity 21 of the implant 20 via the axial through hole 101 of the abutment 100, as illustrated in FIG. 3B. The abutment 100 is further provided in the lateral side of the upper segment thereof with a lateral threaded hole 102. The abutment 100 is fastened with the incisor “T” by another fastening screw “S” which is engaged with the lateral threaded hole 102, as shown in FIG. 3C.
Referring to FIG. 4A of the drawing, the implantation angle θ is likely deviated in the implantation operation of the implant 20 such that the implantation angle θ1 may be too large, as shown in FIG. 4B, or that the implantation angle θ2 may be too small, as shown in FIG. 4C. Such angular deviations as described above often result in failure of implantation. With the purpose of overcoming the drawback of the angular deviation, a variety of abutments 100, 110, 120, etc, must be prepared at additional cost, which is of course passed on to the patient under treatment. The pre-operational X-cay diagnosis is of a little help in determining the implantation angle of the implant 20 in conformity with the specification of the abutment 100. In addition, there is lack of a standardized implantation method by which the implant 20 is always implanted into the socketed bone “I” at a correct angle. As a result, the abutment 100 must be mended by the dental technician at additional cost.